Solid state image pickup

ABSTRACT

In a solid state image pickup apparatus employing a solid state image pickup device of the interline transfer type which comprises a plurality of photodetectors (1) arranged horizontally and vertically, transfer gate areas (6) each corresponding to each of the photodetectors (1), vertical transfer portions (2), a horizontal transfer portion (4) and an output portion (5), a reading pulse voltage taking a first high level (V R ) is applied to each of two of the transfer gate areas (6) adjacent in the vertical direction alternately at every field period, so that signal charges are read out to the vertical transfer portions (2) from the photodetectors (1) corresponding to the transfer gate areas (6) to which the reading pulse voltage is applied, a voltage taking a second high level (V H ) lower than the first high level (V R ) is applied to the storage regions of the vertical transfer portions (2) during each horizontal video period, transfer pulse voltages taking the low level (V L ) in turn at the respective different phases within each horizontal blanking period are applied to the vertical transfer portions (2), so that the signal charges read out to the vertical transfer portions (2) are transferred vertically, and the signal charges transferred vertically are further transferred horizontally through the horizontal transfer portion (4) to the output portion (5), thereby to produce an image pickup signal output.

TECHNICAL FIELD

This invention relates to solid state image pickup apparatus employing asolid state image pickup device which comprises a charge transferdevice, and more particularly, is directed to an improved solid stateimage pickup apparatus employing a solid state image pickup device ofthe interline transfer type, in which the driving condition for chargetransfer performed in the solid state image pickup device is contrivedso that a certain defect on a reproduced picture obtained in response toan image pickup signal output derived therefrom is eliminated.

TECHNICAL BACKGROUND

Solid state image pickup devices comprising a charge transfer devicesuch as a charge coupled device ( hereinafter referred to as a CCD ) areclassified broadly into the frame transfer type and the interlinetransfer type, and each of them is utilized in different way so as tomake a good use of its advantages and features. One example of the solidstate image pickup device of the interline transfer type using the CCDcomprises a photo-sensing and vertical transfer portion which includes aplurality of photodetectors arranged in horizontal and vertical rows andvertical transfer portions each formed with a group of CCDs andextending along each of the vertical rows of the photodetectors, ahorizontal transfer portion coupled with the photo-sensing and verticaltransfer portion and an output portion coupled with the horizontaltransfer portion and provided with an signal output terminal, the wholeof which are formed on a common semiconductor substrate.

In a solid state image pickup apparatus employing such a solid stateimage pickup device of the interline transfer type using the CCD, avertical driving signal for vertical charge transfer is applied to thevertical transfer portions through vertical transfer electrodes whichare provided on an insulating layer overspreading the photosensing andvertical transfer portion and a horizontal driving signal for horizontalcharge transfer is applied to the horizontal transfer portion throughhorizontal transfer electrodes which are provided on an insulating layeroverspreading the horizontal transfer portion, so that vertical chargetransfer operation and horizontal charge transfer operation areperformed in the vertical transfer portions and the horizontal transferportion, respectively. For example, signal charges obtained in thephotodetectors in response to the light received thereby during oneframe period are read out to the vertical transfer portions, and thentransferred toward the horizontal transfer portion by the verticalcharge transfer operation performed in the vertical transfer portion sothat the signal charges produced in each horizontal row of thephotodetectors are transferred in turn to the horizontal transferportion. The signal charges transferred to the horizontal transferportion are further transferred to the output portion by the horizontalcharge transfer operation performed in the horizontal transfer portionand as a result of this an image pickup signal output is obtained at thesignal output terminal.

When a picture is reproduced in response to an image pickup signaloutput obtained under such operation of the solid state image pickupdevice of the interline transfer type as described above in apreviousely proposed solid state image pickup apparutus, it is oftenseen that such a defect as to appear to be a pair of black and whitespots contiguous up and down to each other arises on the reproducedpicture. This defect is usually called "white and black spots", and theblack spot therein tends to elongate when the image pickup signal outputis produced under relatively low illuminance. Such white and black spotscan not be eliminated by means of ordinary defect correction, becausethey result from a local area of deep ( high ) potential residing in thevertical transfer portion. This local area of deep potential in thevertical transfer portion appears at a region having high impuritydensity which is provided undesirably due to nonuniformity in impuritydensity in the vertical transfer portion or at a region positioned undera thick portion of the insulating layer which is provided undesirablydue to nonuniformity in thickness of the insulating layer on thevertical transfer portion, and is a structural defect in the imagepickup device.

In the case of the image pickup device in which such a local area ofdeep potential in the vertical transfer portion as described aboveresides, an insulated gate field effect transistor ( hereinafterreferred to as a MOS FET ) having its source at the local area of deeppotential is substantially formed in the vertical transfer portion and aflow of charges is caused from the local area of deep potential to anadvanced potential well in the vertical transfer portion as asub-threshold current of the MOS FET. If a charge transfer period inwhich each charge transfer in the vertical transfer portions is carriedout is constant and the manner of repetition of such charge transferperiods is made uniform, the amount of charges flowing into the advancedpotential well from the local area of deep potential is not varied andtherefore the charges flowing into the advanced potential well from thelocal area of deep potential do not raise any serious problem. However,as to the charge transfer operation in the vertical transfer portions,an exceptional situation in which the charge transfer period iselongated in comparison with that in the normal situation arises, forexample, once a frame period, and during such elongated charge transferperiod, the local area of deep potential sends the charges storedtherein in large quantities into the advanced potential well so as tosupply excessive signal charges to the latter and, to the contrary, tomake areas positioned behind be lacking in signal charges. This resultsin that the signal charges are in unbalanced quantities so that an imagepickup signal output developed therefrom is deteriorated and the whiteand black spots appear on a picture reproduced in response to thedeteriorated image pickup signal output.

In view of the cause of the white and black spots mentioned above, it isunderstood that the problem of the white and black spots can be solvedby means of maintaining the charge transfer period, in which each chargetransfer in the vertical transfer portions is carried out, to beconstant regardless of the operation for reading out the signal chargesto the vertical transfer portions from the photodetectors.

Accordingly, it is an object of the present invention to provide ansolid state image pickup apparatus employing a solid state image pickupdevice of the interline transfer type, in which the driving conditionfor charge transfer performed in vertical transfer portions provided inthe solid state image pickup device is improved so that a chargetransfer period in which each charge transfer in the vertical transferportions is carried out is made uniform and consequently an image pickupsignal output from which a picture without the defect called usually"white and black spots" is reproduced can be obtained from theapparatus.

DISCLOSURE OF THE INVENTION

According to an aspect of the present invention, in a solid state imagepickup apparatus employing a solid state image pickup device of theinterline transfer type which comprises a plurality of photodetectorsarranged vertically and horizontally, transfer gate areas eachcorresponding to each of the photodetectors, vertical transfer portions,a horizontal transfer portion and an output portion; a reading pulsevoltage taking a first high level is applied to each of two transfergate areas adjacent in the vertical direction alternately at every fieldperiod, a voltage taking a second high level lower than the first highlevel is applied to the storage regions of the vertical transferportions during each horizontal video period, and transfer pulsevoltages taking a low level in turn at the respective different phaseswithin each horizontal blanking period are applied to the verticaltransfer portions. In this driving manner for making the solid stateimage pickup device operative, signal charges are read out to thestorage regions of the vertical transfer portions from thephotodetectors corresponding to the transfer gate areas to which thereading pulse voltage taking the first high level is applied, thentransferred vertically through the vertical transfer portions to thehorizontal transfer portion in response to the transfer pulse voltagesapplied to the vertical transfer portions in the horizontal blankingperiod and further transferred horizontally through the horizontaltransfer portion to the output portion.

With the solid state image pickup apparatus thus constituted inaccordance with the present invention, even if the solid state imagepickup device of the interline transfer type employed therein contains adefective local area having deep potential in the vertical transferportions, an image pickup signal output, which is produced in accordancewith the frame interlace reading manner and does not cause a defect on apicture reproduced therefrom which otherwith would be resulted from thedefective local area in the image pickup device, can be obtained.Futher, since the image pickup device containing therein such adefective local area can be used as a normal device, the yield rate inmanufacturing is substantially improved. Moreover, since the rate oftimes in which both of vertical driving signals supplied at therespective different phases to vertical transfer electrodes provided onthe image pickup device take a high level voltage is increased, such anadditional effect that an overflow drain formed with a buried channel inthe image pickup device is stabilized in its operation and smearsarising in the first and second field periods constituting each frameperiod are reduced to an average so that the difference in brightnessbetween each two field pictures reproduced in response to the imagepickup signal output derived from the apparatus is reduced, can beobtained.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic plane view showing one example of a solid stateimage pickup device of the interline transfer type comprising a CCD;

FIGS. 2-A and 2-B are plane and sectional views respectively showing anenlarged portion of the device shown in FIG. 1;

FIGS. 3-A and 3-B are waveform diagrams showing one example of a set ofdriving signals used for a photosensing and vertical transfer portion ofa solid state image pickup device employed in a previously proposedsolid state image pickup apparatus;

FIG. 4 is a sectional view showing a portion of another example of asolid state image pickup device of the interline transfer typecomprising a CCD;

FIGS. 5-A, 5-B and 5-C are waveform diagrams showing another example ofa set of driving signals used for a photo-sensing and vertical transferportion of a solid state image pickup device employed in a previouslyproposed solid state image pickup apparatus;

FIG. 6 is an illustration used for explaining occurrence of the defectof white and black spots;

FIGS. 7-A, 7-B, 8-A and 8-B are waveform diagrams showing a set ofdriving signals used for a photo-sensing and vertical transfer portionof a solid state image pickup device employed in one embodiment of thepresent invention;

FIG. 9 is a plane view showing an enlarged portion of a solid stateimage pickup device employed in another embodiment of the presentinvention; and

FIGS. 10-A, 10-B, 10-C and 10-D are waveform diagrams showing a set ofdriving signals used for a photosensing and vertical transfer portion ofthe solid state image pickup device having the portion shown in FIG. 9.

EMBODIMENTS MOST PREFERABLE FOR WORKING OF THE INVENTION

First, to facilitate understanding of the embodiments of the invention,the configuration of a solid state image pickup device of the interlinetransfer type and the operation of such a solid state image pickupdevice employed in a previously proposed solid state image pickupapparatus will be explained with reference to FIGS. 1 to 6.

An example of a solid state image pickup device of the interlinetransfer type using a CCD is constituted as shown in FIG. 1, andcomprises a photo-sensing and vertical transfer portion 3 which includesa plurality of photodetectors 1 arranged in horizontal and vertical rowsand vertical transfer portions 2 each formed with a group of CCDs andprovided along each of the vertical rows of the photodetectors 1, ahorizontal transfer portion 4 coupled with the photo-sensing andvertical transfer portion 3 and an output portion 5 coupled with thehorizontal transfer portion 4 and provided with a signal output terminal5a, the whole of which are formed on a common semiconductor substrate.

In a solid state image pickup apparatus employing such a solid stateimage pickup device as mentioned above, a predetermined verticaltransfer driving signal and a predetermined horizontal transfer drivingsignal are applied to the vertical transfer portions 2 and thehorizontal transfer portion 4, respectively, so that vertical andhorizontal charge transfers are performed in the solid state imagepickup device. With such driving signals, signal charges obtained in thephotodetectors 1 in response to the light received thereby during forexample, one frame period are read out to the vertical transfer portions2 and then transferred vertically toward the horizontal transfer portion4 by the charge transfer operation of the vertical transfer portions 2during each horizontal blanking period so that the signal chargesproduced in each horizontal row of the photodetectors 1 are transferredin turn to the horizontal transfer portion 4. The signal chargestransferred to the horizontal transfer portion 4 are further transferredhorizontally to the output portion 5 by the charge transfer operation ofthe horizontal transfer portion 4 during each horizontal video periodand as a result of this an image pickup signal output is obtained at thesignal output terminal 5a.

Going into details, the photo-sensing and vertical transfer portion 3mentioned above contains transfer gate areas 6 provided between eachvertical row of the photodetectors 1 and the corresponding one of thevertical transfer portions 2 and a channel stop area 7 provided aroundeach of the photodetectors 1, as shown in FIG. 2-A. Further, an overflowdrain 8 is provided to be contiguous to each of the channel stop areas 7and each of the overflow drains 8 and the corresponding one of thevertical transfer portions 2 are separated by a channel stop area 9. Onthe vertical transfer portions 2, vertical transfer electrodes Φ₁ and Φ₂each elongating in the horizontal direction are provided alternately inthe vertical direction. Each vertical transfer electrode Φ₁ is composedof a charge storage electrode Φ_(1c) and a charge transfer electrode(potential barrier electrode ) Φ_(1t), and each vertical transferelectrode Φ₂ is composed of a charge storage electrode Φ_(2c) and acharge transfer electrode Φ_(2t). In the vertical transfer portions 2,storage regions are formed under the charge storage electrods Φ_(1c) andΦ_(2c) and transfer regions (potential barrier regions ) are formedunder the charge transfer electrodes Φ_(1t) and Φ_(2t), and eachtransfer region is subjected to the ion implantation or provided thereonwith a thick insulating layer so as to have a potential shallower (lower) than that of the storage region adjacent thereto and to form apotential barrier. As shown in FIG. 2-B which shows a sectional view atthe position indicated by arrows IIB--IIB in FIG. 2-A, the abovementioned portions and areas are formed on a semiconductor substrate 10of, for example, the P type and an insulating layer 11 is provided tocover the whole of these portions and areas thereby with the verticaltransfer electrodes (Φ₂) provided thereon. In this example, the verticaltransfer electrodes Φ₁ and Φ₂ include transfer gate electrodes atportions thereof, and therefore in FIG. 2-B, the vertical transferelectrode Φ₂ (more exactly, the charge storage electrode Φ_(2c) of thevertical transfer electrode Φ₂) is extended to cover the transfer gatearea 6.

In the previously proposed solid state image pickup apparatus employingthe solid state image pickup device of the interline transfer type thusconstituted, the vertical transfer electrodes Φ₁ and Φ₂ on thephoto-sensing and vertical transfer portion 3 of the solid state imagepickup device are supplied with driving signals Φ₁ and Φ₂ as shown inFIGS. 3-A and 3-B, respectively, and the voltages of thses drivingsignals Φ₁ and Φ₂ are applied to the transfer gate areas 6 and thevertical transfer portions 2 positioned under the vertical transferelectrodes Φ₁ and Φ₂. With such driving signals Φ₁ and Φ₂, the signalcharges stored in each two photodetectors 1 adjacent vertically to eachother are read out throuth the transfer gate areas 6 to the verticaltransfer portions 2 from one of the two photodetectors 1 alternately atevery field period so that the signal charges obtained in thephotodetectors 1 are read out in the frame interlace reading manner, andthe signal charges read out to the vertical transfer portions 2 aretransferred vertically to the horizontal transfer portion 4. To achievesuch operation, the driving signals Φ₁ and Φ₂ have reading pulses R₁ andR₂ of high level appearing at every frame period, respectively, and alsotransfer pulses Q₁ and Q₂ appearing with opposite phases at eachhorizontal blanking period, respectively. The signal charges aretransferred vertically with the high level of the transfer pulse Q₁ andthe low level of the transfer pulse Q₂.

When the reading pulse R₂ of driving signal Φ₂ is supplied to thevertical transfer electrodes Φ₂, the voltage of the reading pulse R₂ isapplied to a first group of the transfer gate areas 6 under the verticaltransfer electrodes Φ₂ and the signal charges stored during one frameperiod in the photodetectors 1 corresponding to the first group of thetransfer gate areas 6 are read out to the vertical transfer portions 2as signal charges for the first field. Then, the signal charges read outto the vertical transfer portions 2 in response to the reading pulse R₂are transferred vertically at each horizontal blanking period accordingto the voltages of the transfer pulses Q₁ and Q₂ applied to the verticaltransfer portions 2 under the vertical transfer electrodes Φ₁ and Φ₂.After that, when the reading pulse R₁ of the driving signal Φ₁ issupplied to the vertical transfer electrodes Φ₁, the voltage of thereading pulse R₁ is applied to a second group of the transfer gate areas6 under the vertical transfer electrodes Φ₁ and the signal chargesstored during one frame period in the photodetectors 1 corresponding tothe second group of the transfer gate areas 6 are read out to thevertical transfer portions 2 as signal charges for the second field.Then, the signal charges read out to the vertical transfer portions 2 inresponse to the reading pulse R₁ are transferred vertically at eachhorizontal blanking period according to the voltages of the transferpulses Q₁ and Q₂ applied to the vertical transfer portions 2 under thevertical transfer electrodes Φ₁ and Φ₂. The reading and transferringoperation mentioned above is performed repeatedly.

In the case of a previously proposed solid state image pickup apparatusemploying a solid state image pickup device of the interline transfertype in which independent transfer gate electrodes Ω are provided asshown in FIG. 4, two-level driving signals φ₁ ' and φ₂ ' having thetransfer pulses Q₁ and Q₂, respectively, as shown in FIGS. 5-A and 5-Bare supplied to the vertical transfer electrodes Φ₁ and Φ₂,respectively, and a reading pulse R' appearing at every field period asshown in FIG. 5-C is supplied to the transfer gate electrodes Ω. Whenthe reading pulse R' is supplied to the transfer gate electrodes Ω, thesignal charges in the photodetectors 1 corresponding to the transfergate areas 6 which are contiguous to the regions in the verticaltransfer portions 2 to which the voltage of the high level of either thedriving signal φ₁ ' or φ₂ ' is applied are read out to the verticaltransfer portions 2. The vertical transfer of the signal charges arecarried out in response to the transfer pulses Q₁ and Q₂ in the samemanner as taken in the device shown in FIGS. 2-A and 2-B.

When a picture is reproduced in response to the image pickup signaloutput obtained at the signal output terminal 5a of the solid stateimage pickup device employed in such previously proposed solid stateimage pickup apparatus as described above, the aforementioned white andblack spots would be caused on the reproduced picture by a local area ofdeep potential that is, a local area with abnormally deep potentialformed in the vertical transfer portions 2 of the solid state imagepickup device. FIG. 6 shows a situation in which such a local area ofdeep potential as to cause the white and black spots is madeundesirably. In FIG. 6, the steps in the storage regions P_(c) and thetransfer regions P_(t) under the charge storage electrodes Φ_(1c) andΦ_(2c) and the charge transfer electrodes Φ_(1t) and Φ_(2t), which formthe vertical transfer electrodes Φ₁ and Φ₂, show the depth of potentialof the respective regions in process of charge transfer in the verticaltransfer portion 2, which increases below, and x indicates the localarea of deep potential formed undesirably in the vertical transferportion 2. In this case, a MOS FET having its source S made of the areax, its gate G made of the storage region P_(c) under the charge storageelectrode Φ_(1c) and its drain D made of the transfer region P_(t) underthe charge transfer electrode Φ_(2t) is substantially formed and a flowof charges arises from the area x under the vertical transfer electrodeΦ₁ to an advanced potential well in the regions under the verticaltransfer electrode Φ₂ as a sub-threshold current of the MOS FET. If acharge transfer period in which each charge transfer in the verticaltransfer portion 2 is carried out is constant and the interval betweensuch charge transfer periods is made uniform, the amount of chargesflowing from the area x to the advanced potential well is not varied andtherefore the charges flowing into the advanced potential well do notraise any troublesome problem. However, as described above, the chargetransfer in the vertical transfer portion 2 is carried out in responseto the driving signals φ₁ and φ₂ shown in FIGS. 3-A and 3-B or thedriving signals φ₁ ' and φ₂ ' shown in FIGS. 5-A and 5-B, andconsequently, a long charge transfer period T appears once a frameperiod, as shown in FIGS. 3-A and 3-B or the FIGS. 5-A and 5-B. In thecase of these driving signals, the long charge transfer period T appearsto include a reading out period in which the signal charges for thesecond field are read out to the vertical transfer portion 2. Duringthis long charge transfer period T, the area x transfers the chargesstored therein in large quantities compared with the normal amount ofcharges to the advanced potential well so as to supply excessive signalcharges to the latter and, to the contrary, to make the regionspositioned behind be lacking in signal charges. This causes the whiteand black spots in such a manner as aforementioned.

Now, preferred embodiments of the present invention will be explained indetail hereinafter.

One example of a solid state image pickup apparatus according to thepresent invention is constituted with the solid state image pickupdevice having the configuration shown in FIGS. 1, 2-A and 2-B andtwo-phase driving signals φ₁₁ and φ₁₂ shown in FIGS. 7-A and 7-B, whichare supplied to the vertical transfer electrodes Φ₁ and Φ₂ of the solidstate image pickup device, respectively. The driving signals φ₁₁ and φ₁₂are formed into three-level signals, respectively. The driving signalφ₁₁ contains a reading pulse R₁₁ taking a first high level V_(R) and atransfer pulse Q₁₁ appearing with the low level V_(L) in each horizontalblanking period and further takes a second high level V_(H) lower thanthe first high level V_(R) during each horizontal video period. Thedriving signal φ₁₂ contains a reading pulse R₁₂ taking the first highlevel V_(R) and a transfer pulse Q₁₂ appearing with the low level V_(L)in each horizontal blanking period and further takes the second highlevel V_(H) during each horizontal video period. The transfer pulses Q₁₁and Q₁₂ take the respective phases different from each other in eachhorizontal blanking period.

FIG. 8 shows in enlarged scale the portions of the driving signals φ₁₁and φ₁₂ encircled with a broken line in FIG. 7-A and 7-B. As shown inFIG. 8, the transfer pulses Q₁₁ and Q₁₂, each of which has the pulsewidth τ₁ of about 2 μsec, appear with the time difference τ₂ of about 3μsec between them within the horizontal blanking period H_(B), and eachof the reading pulses R₁₁ and R₁₂ has the pulse width τ₃ of about 20 μsec. With the supply of these driving signals φ₁₁ and φ₁₂, the voltagehaving the second high level V_(H) is applied to the storage regions ofthe vertical transfer portions 2 under the charge storage electrodesΦ_(1c) and Φ_(2c) and the transfer regions of the vertical transferportions 2 under the charge transfer electrodes Φ_(1t) and Φ_(2t) duringeach horizontal video period, and the charge transfer in the verticaltransfer portions 2 is carried out when the voltage having the low levelV_(L) of the transfer pulse Q₁₁ is first applied to the regions underthe vertical transfer electrodes Φ₁ and then the voltage having the lowlevel V_(L) of the transfer pulse Q₁₂ is applied to the regions underthe vertical transfer electrodes Φ₂ within each horizontal blankingperiod.

Further, the transfer of signal charges from the photodetectors 1 to thevertical transfer portions 2 is performed as mentioned below.

When the reading pulse R₁₂ of the driving signal φ₁₂ is supplied to thevertical transfer electrodes φ₂, the voltage having the first high levelV_(R) of the reading pulse R₁₂ is applied to the transfer gate areas 6under the charge storage electrodes Φ_(2c) and the signal charges storedduring one frame period in the photodetectors 1 corresponding to thetransfer gate areas 6 under the charge storage electrodes Φ_(2c) areread out to the storage regions of the vertical transfer portions 2under the charge storage electrodes Φ_(2c) as signal charges for thefirst field. After that, when the reading pulse R₁₁ of the drivingsignal φ₁₁ is supplied to the vertical transfer electrodes Φ₁, thevoltage having the first high level V_(R) of the reading pulse R₁₁ isapplied to the transfer gate areas 6 under the charge storage electrodesΦ_(1c) and the signal charges stored during one frame period in thephotodetectors 1 corresponding to the transfer gate areas 6 under thecharge storage electrodes Φ_(1c) are read out to the storage regions ofthe vertical transfer portions 2 under the charge storage electrodesΦ_(1c) as signal charges for the second field. This reading operation isperformed repeatedly and as a result the signal charges obtained in thephotodetectors 1 are read out in the frame interlace manner.

The amplitude V_(R) -V_(H) of each of the reading pulses R₁₁ and R₁₂ isselected to be smaller than the amplitude V_(H) -V_(L) of each of thetransfer pulses Q₁₁ and Q₁₂, so that the reading pulse R₁₁ or R₁₂ isprevented from making such potential steps in the vertical transferportions 2 as will cause charge transfer in the vertical transferportions 2.

In addition, it is preferable to provide a vertical output gate portionat the end of each of the vertical transfer portions 2 and make thevertical output gate portions be in the ON state in response to thetransfer pulse Q₁₁ or Q₁₂ so as to transfer the signal charges to thehorizontal transfer portion 4 from the vertical transfer portions 2 inorder to prevent the signal charges being in process of transfer in thehorizontal transfer portion 4 from flowing into the vertical transferportions 2.

As described above, with the two-phase driving signals φ₁₁ and φ₁₂supplied to the vertical transfer electrodes Φ₁ and Φ₂, the signalcharges obtained in the photodetectors 1 are read out to the verticaltransfer portions 2 in the frame interlace manner. Further, since thesignal charges read out to the vertical transfer portions 2 aretransferred in the vertical transfer portions 2 only during the periodsof the transfer pulses Q₁₁ and Q₁₂ within each horizontal blankingperiod, the charge transfer period in which each charge transfer in thevertical transfer portions 2 is carried out is kept constant and theinterval between such charge transfer periods is made uniform and, as aresult of this, an image pickup signal output from which a picturewithout the white and black spots thereon is reproduced can be obtainedat the signal output terminal 5a.

Although the solid state image pickup device having the verticaltransfer portions which are drived to be operative by the two-phasedriving signals is employed in the embodiment described above, a solidstate image pickup device having vertical transfer portions which arearranged to be drived by a four-phase driving signals can be used forthe solid state image pickup apparatus according to the presentinvention.

FIG. 9 shows the configuration of a photosensing and vertical transferportion in the solid state image pickup device having the verticaltransfer portions which are arranged to be drived by the four-phasedriving signals employed in another embodiment of the present invention.

In FIG. 9, portions and areas corresponding to those of FIG. 2-A aremarked with the same references. In this case, vertical transferelectrodes Φ₁ ', Φ₂ ', Φ₃ ' and Φ₄ ' are independent and arranged inorder repeatedly. The vertical transfer electrodes Φ₁ ' and Φ₃ ' includerespective transfer gate electrodes at the portions thereof.

FIGS. 10-A, 10-B, 10-C and 10-D show four-phase driving signals φ₁₁ ',φ₁₂ ', φ₁₃ ' and φ₁₄ ' which are supplied to the vertical transferelectrodes Φ₁ ', Φ₂ ', Φ₃ ' and Φ₄ ' of the device shown in FIG. 9,respectively.

With such four-phase driving signals φ₁₁ ', φ₁₂ ', φ₁₃ ' and φ₁₄ ', inthe vertical transfer portions 2, the storage regions are formed underthe vertical transfer electrodes Φ₁ ', Φ₃ ' and Φ₄ ' and the transferregions are formed under the vertical transfer electrodes Φ₂ '. Thesignal charges obtained in the photodetectors 1 are read out to thevertical transfer portions 2 at every field period in the frameinterlace manner in response to reading pulses R₁₁ ' and R₁₃ ' takingthe first high level V_(R) and contained in the driving signals φ₁₁ 'and φ₁₃ ', respectively, and the voltage having the second high levelV_(H) is applied to the storage regions in the vertical transferportions 2 during each horizontal video period.

Although, in this embodiment, the voltage having the low level V_(L) ofthe driving signal φ₁₂ ' only the transfer regions of the verticaltransfer portions 2 under the vertical transfer electrodes Φ₂ ' duringeach horizontal video period, it is also possible to arrange so that thetransfer regions of the vertical transfer portions 2 are formed underthe vertical transfer electrodes Φ₄ ' and the voltage having the lowlevel V_(L) is applied to the transfer regions under the verticaltransfer electrodes Φ₄ ' during each horizontal video period.

In this embodiment, the charge transfer in the vertical transferportions 2 is carried out when the driving signal φ₁₂ ' takes the secondhigh level V_(H) and the transfer pulses taking the low level V_(L) andcontained in the driving signals Φ₁₁ ', Φ₁₃ ' and Φ₁₄ ', respectively,appear with the respective different phases within each horizontalblanking period. When the charge transfer operation is performed in thevertical transfer portions 2, the voltage having the second high levelV_(H) is applied to the regions in the vertical transfer portions 2under two or three adjacent ones of the vertical transfer electrodes Φ₁' to Φ₄ ' simultaneously so that the potential well is formed in turn inthese regions. This results in the increased charge transfer efficiency.The amplitude V_(R) -V_(H) of each of the reading pulses R₁₁ ' and R₁₃ 'is selected to be smaller than the amplitude V_(H) -V_(L) of each of thetransfer pulses appearing in the horizontal blanking period for the samereason as aforementioned.

In this case also, the charge transfer period in which each chargetransfer in the vertical transfer portions 2 is carried out is keptconstant and the interval between the charge transfer periods is madeuniform and consequently an image pickup signal output from which apicture without the white and black spots thereon is reproduced can beobtained.

Applicability for Industrial Use

As described above, the solid state image pickup apparatus according tothe present invention can produce an image pickup signal output beingsuperior in quality, from which a picture without the white and blackspots thereon is reproduced, and therefore is quite suitable forconstituting a high-grade television camera miniaturized in size andlightened in weight.

I claim:
 1. A solid state image pickup apparatus employing a solid stateimage pickup device which comprises a plurality of photodetectorsarranged horizontally and vertically, transfer gate areas eachcorresponding to each of the photodetectors, a plurality of verticaltransfer portions comprising charge coupled devices each extendingvertically and positioned contiguously to the transfer gate areas whichhave transfer areas and storage regions, and a horizontal transferportion coupled with the end of each of the vertical transfer portionsand an output portion, wherein a reading pulse voltage which takes afirst high level is applied to an even numbered rows of transfer gatesduring even field periods and is applied to odd numbered rows oftransfer gates during odd field periods, so that signal charges are readout from said storage regions of said vertical transfer portions, avoltage which takes a second high level which is lower than said firsthigh level is applied to said storage regions of said vertical transferportions during each horizontal video period, transfer pulse voltageswhich take a low level at respective different phases within eachhorizontal blanking period are applied to said vertical transferportions, so that the signal charges which are read out to said verticaltransfer portions are transferred vertically to said horizontal transferportion, and the signal charges which have been transferred to thehorizontal transfer portion are further transferred in the horizontaldirection through the horizontal transfer portion to an output portion.